Edge‐on disk galaxies in the SDSS DR6: Fractions of bulgeless and other disk galaxies

The aim of this study is to determine the fractions of different spiral galaxy types, especially bulgeless disks, from a complete and homogeneous sample of 15 127 edge‐on disk galaxies extracted from the sixth data release from the Sloan Digital Sky Survey. The sample is divided in broad morphological classes and sub types consisting of galaxies with bulges, intermediate types and galaxies which appear bulgeless. A small fraction of disky irregulars is also detected. The morphological separation is based on automated classification criteria which resemble the bulge sizes and the flatness of the disks. Each of these broad classes contains about 1/3 of the total sample. Using strict criteria for selecting pure bulgeless galaxies leads to a fraction of 15% of simple disk galaxies. We compare this fraction to other galaxy catalogs and find an excellent agreement of the observed frequency of bulgeless galaxies. Although the fraction of simple disk galaxies in this study does not represent a “cosmic” fraction of bulgeless galaxies, it shows that the relative abundance of pure disks is comparable to other studies and offers a profound value of the frequency of simple disks in the local Universe. This fraction of simple disks emphasizes the challenge for formation and evolution models of disk galaxies since these models are hard pressed to explain the observed frequency of these objects (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Systematic Time Delay of Hemispheric Solar Activity

Five solar-activity indices – the monthly-mean sunspot numbers from January 1945 to March 2008, the monthly-mean sunspot areas during the period of May 1874 to March 2008, the monthly numbers of sunspot groups from May 1874 to May 2008, the monthly-mean flare indices from January 1966 to December 2006, and the numbers of solar filaments per Carrington rotation in the time interval of solar rotations 876 to 1823 – have been used to show a systematic time delay between northern and southern hemispheric solar activities in a cycle. It is found that solar activity does not occur synchronously in the northern and southern hemispheres, and there is a systematic time lag or lead (phase shift) between northern and southern hemispheric solar activity in a cycle. About an eight-cycle period is inferred to exist in such phase shifts. The activity on the Sun may be governed by two different and coupled processes, not by a single process.     

The Long-term Behavior of the North – South Asymmetry of Sunspot Activity

A new index, the cumulative difference of sunspot activity in the northern and southern hemispheres, respectively, is proposed to describe the long-term behavior of the North – South asymmetry of sunspot activity and to show the balance (or bias) of sunspot activity in the two solar hemispheres on a long-term scale. Sunspot groups and sunspot areas from June 1874 to January 2007 are used to show the advantage of the index. The index clearly shows a long-term characteristic time scale of about 12 cycles in the North – South asymmetry of sunspot activity. Sunspot activity is found to dominate in the southern hemisphere in cycle 23, and in cycle 24 it is predicted to dominate still in the southern hemisphere. A comparison of the new index with other similar indexes is also given.     

Bulge–disc decompositions and structural bimodality of Ursa Major cluster spiral galaxies

We present bulge and disc (B/D) decompositions of existing   K '  surface brightness profiles for 65 Ursa Major (UMa) cluster spiral galaxies. This improves upon the disc-only fits of Tully et al. The 1996 disc fits were used by Tully & Verheijen for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new one-dimensional B/D decompositions yield disc structural parameters that differ only slightly from the basic fits of Tully et al. and evidence for structural bimodality of UMa galaxies is maintained. Our B/D software for the decomposition of one-dimensional surface brightness profiles of galaxies uses a non-linear minimization scheme to recover the best-fitting Sérsic bulge and the exponential disc while accounting for the possible presence of a compact nucleus and spiral arms and for the effects of seeing and disc truncations. In agreement with Tully & Verheijen, we find that the distribution of near-infrared disc central surface brightnesses is bimodal with an F-test confidence of 80 per cent. There is also strong evidence for a local minimum in the luminosity function at     . A connection between the brightness bimodality and a dynamical bimodality, based on new H  i linewidths, is identified. The B/D parameters are presented in Table 1 .  

  Table 1.  B/D parameters.     

936.

Incorporating photometric redshift probability density information into real-space clustering measurements     

Adam D. Myers  Martin White  Nicholas M. Ball 《Monthly notices of the Royal Astronomical Society》2009,399(4):2279-2287

The use of photometric redshifts in cosmology is increasing. Often, however these photo- z are treated like spectroscopic observations, in that the peak of the photometric redshift, rather than the full probability density function (PDF), is used. This overlooks useful information inherent in the full PDF. We introduce a new real-space estimator for one of the most used cosmological statistics, the two-point correlation function, that weights by the PDF of individual photometric objects in a manner that is optimal when Poisson statistics dominate. As our estimator does not bin based on the PDF peak, it substantially enhances the clustering signal by usefully incorporating information from all photometric objects that overlap the redshift bin of interest. As a real-world application, we measure quasi-stellar object (QSO) clustering in the Sloan Digital Sky Survey (SDSS). We find that our simplest binned estimator improves the clustering signal by a factor equivalent to increasing the survey size by a factor of 2–3. We also introduce a new implementation that fully weights between pairs of objects in constructing the cross-correlation and find that this pair-weighted estimator improves clustering signal in a manner equivalent to increasing the survey size by a factor of 4–5. Our technique uses spectroscopic data to anchor the distance scale and it will be particularly useful where spectroscopic data (e.g. from BOSS) overlap deeper photometry (e.g. from Pan-STARRS, DES or the LSST). We additionally provide simple, informative expressions to determine when our estimator will be competitive with the autocorrelation of spectroscopic objects. Although we use QSOs as an example population, our estimator can and should be applied to any clustering estimate that uses photometric objects.     

937.

广东秋冬春连旱的时空变化及环流演变特征   总被引：2，自引：0，他引：2  

梁巧倩  梁玉琼  纪忠萍  吴秀兰  李茵茵 《热带气象学报》2009,25(1):123-128

利用1948—2006年NCEP/NCAR的再分析高空资料以及广东省48个测站的降水资料,综合采用L指数和AWTP指数可对广东秋冬春连旱进行较好的描述;EOF的分析表明广东的秋冬春连旱空间变化具有全省一致性,时间上不仅具有明显的年际变化,还有阶段性变化和趋旱的趋势变化。广东秋冬春连旱异常年份的合成分析表明,从秋季到次年春季,极涡和南支槽的活动都较常年偏弱;秋季华南受偏强的反气旋环流影响,干燥少雨;冬季,小股的冷空气偏东路径活动,低层华南到南海大部有东北风距平,干燥少雨;春季,小股的冷空气频繁东移,华南处高空槽底偏西风场中,低层的西南风较常年偏弱,不利于华南地区冷暖气流的交汇,降水偏少。这些分析结果可为短期气候预测提供依据。     

938.

大地电磁三维反演方法综述   总被引：20，自引：7，他引：13       下载免费PDF全文

胡祖志  胡祥云 《地球物理学进展》2005,20(1):214-220

大地电磁测深（MT）资料的三维正、反演问题,已成为国际地球内部电磁感应领域研究的前沿课题.文中从算法思想方面简要地介绍了当前国内外MT三维反演的几种主要方法,探讨了今后MT三维反演研究的方向.     

939.

Is MSC eco-labelling workable in Taiwan? Responses from various sectors of the Taiwanese sergestid shrimp fishery     

《Marine Policy》2017

Marine Stewardship Council (MSC) eco-labelling is among the widely known market-based management approaches that are considered effective in solving the problem of overfishing. The approach has been applied in several marine capture fisheries worldwide; however, it was found not to be fully workable in many fisheries for various reasons. The sergestid shrimp (Sergia lucens) fishery in Tungkang County of Taiwan has been managed well in recent decades through a bottom-up community-based co-management scheme and is probably the best candidate for obtaining the first MSC certification in Taiwan. This study assessed the fishery in relation to the three principles of MSC eco-labelling and investigated responses from experts, managers, industry representatives, and consumers on improving the fishery in order to obtain the MSC certification. The results suggested that three major problems confronted the fishery: (1) the fishery was unlikely to meet the MSC standards unless it could reduce its high bycatch rate; (2) the economic and/or political benefits were not attractive enough to the relevant sectors for them to cover the high costs and responsibility of obtaining and maintaining the MSC certification; and (3) the fishery was reputed to be well managed without any eco-label, suggesting no strong incentive to obtain one from a management perspective. The benefits of MSC eco-labelling could be consolidated, however, and the role of government was crucial in this regard.     

940.

Traditional fisheries enforcement program: A case of three coastal villages in the eastern part of Oman     

《Marine Policy》2017

     

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Incorporating photometric redshift probability density information into real-space clustering measurements

The use of photometric redshifts in cosmology is increasing. Often, however these photo- z are treated like spectroscopic observations, in that the peak of the photometric redshift, rather than the full probability density function (PDF), is used. This overlooks useful information inherent in the full PDF. We introduce a new real-space estimator for one of the most used cosmological statistics, the two-point correlation function, that weights by the PDF of individual photometric objects in a manner that is optimal when Poisson statistics dominate. As our estimator does not bin based on the PDF peak, it substantially enhances the clustering signal by usefully incorporating information from all photometric objects that overlap the redshift bin of interest. As a real-world application, we measure quasi-stellar object (QSO) clustering in the Sloan Digital Sky Survey (SDSS). We find that our simplest binned estimator improves the clustering signal by a factor equivalent to increasing the survey size by a factor of 2–3. We also introduce a new implementation that fully weights between pairs of objects in constructing the cross-correlation and find that this pair-weighted estimator improves clustering signal in a manner equivalent to increasing the survey size by a factor of 4–5. Our technique uses spectroscopic data to anchor the distance scale and it will be particularly useful where spectroscopic data (e.g. from BOSS) overlap deeper photometry (e.g. from Pan-STARRS, DES or the LSST). We additionally provide simple, informative expressions to determine when our estimator will be competitive with the autocorrelation of spectroscopic objects. Although we use QSOs as an example population, our estimator can and should be applied to any clustering estimate that uses photometric objects.     

广东秋冬春连旱的时空变化及环流演变特征

利用1948—2006年NCEP/NCAR的再分析高空资料以及广东省48个测站的降水资料,综合采用L指数和AWTP指数可对广东秋冬春连旱进行较好的描述;EOF的分析表明广东的秋冬春连旱空间变化具有全省一致性,时间上不仅具有明显的年际变化,还有阶段性变化和趋旱的趋势变化。广东秋冬春连旱异常年份的合成分析表明,从秋季到次年春季,极涡和南支槽的活动都较常年偏弱;秋季华南受偏强的反气旋环流影响,干燥少雨;冬季,小股的冷空气偏东路径活动,低层华南到南海大部有东北风距平,干燥少雨;春季,小股的冷空气频繁东移,华南处高空槽底偏西风场中,低层的西南风较常年偏弱,不利于华南地区冷暖气流的交汇,降水偏少。这些分析结果可为短期气候预测提供依据。     

大地电磁三维反演方法综述

大地电磁测深（MT）资料的三维正、反演问题,已成为国际地球内部电磁感应领域研究的前沿课题.文中从算法思想方面简要地介绍了当前国内外MT三维反演的几种主要方法,探讨了今后MT三维反演研究的方向.     

Is MSC eco-labelling workable in Taiwan? Responses from various sectors of the Taiwanese sergestid shrimp fishery

Marine Stewardship Council (MSC) eco-labelling is among the widely known market-based management approaches that are considered effective in solving the problem of overfishing. The approach has been applied in several marine capture fisheries worldwide; however, it was found not to be fully workable in many fisheries for various reasons. The sergestid shrimp (Sergia lucens) fishery in Tungkang County of Taiwan has been managed well in recent decades through a bottom-up community-based co-management scheme and is probably the best candidate for obtaining the first MSC certification in Taiwan. This study assessed the fishery in relation to the three principles of MSC eco-labelling and investigated responses from experts, managers, industry representatives, and consumers on improving the fishery in order to obtain the MSC certification. The results suggested that three major problems confronted the fishery: (1) the fishery was unlikely to meet the MSC standards unless it could reduce its high bycatch rate; (2) the economic and/or political benefits were not attractive enough to the relevant sectors for them to cover the high costs and responsibility of obtaining and maintaining the MSC certification; and (3) the fishery was reputed to be well managed without any eco-label, suggesting no strong incentive to obtain one from a management perspective. The benefits of MSC eco-labelling could be consolidated, however, and the role of government was crucial in this regard.